The fusion or cutting of plastics with laser beams is an advantageous method of manufacturing plastics articles with complex geometry. A prerequisite therefor is that the plastic to be treated absorbs the laser beam which, in the case of the commercial lasers, is at 808 nm, 940 to 980 nm and 1064 nm. It therefore has to be additized or coated with substances which absorb at these wavelengths.
For this purpose, WO-A-2005/102 672 describes IR absorbers based on rylene compounds including quaterrylenetetracarboximides, and also doped tin oxides such as ATO and ITO (antimony tin oxide and indium tin oxide respectively), and metal hexaborides such as lanthanum hexaboride. The quaterrylenetetracarboximides can be used advantageously in combination with the lasers which emit at 808 nm; the longer wavelengths are obtainable with the inorganic absorbers.
For a series of applications, for example for applications in the outdoor sector and in the medical or foods sector, the inorganic absorbers, however, do not have the required stabilities.
The prior German patent application 102005018241.0 describes pentarylene- and hexarylenetetracarboximides whose absorption has been shifted bathochromically relative to the quaterrylenetetracarboximides and extends up to the region around 975 nm.
WO 2007/014902 describes polychromophores based on rylene.
In addition, there is a great need for organic compounds which are suitable as organic semiconductors, in particular n-type semiconductors, and especially for use in organic field-effect transistors and solar cells.
The unpublished PCT/EP2006/070143 describes compounds of the general formula
whereat least one of the R1, R2, R3 and R4 radicals is Br, F or CN,Y1 and Y2 are each O or NRi where Ri is hydrogen or an organyl radical,Z1, Z2, Z3 and Z4 are each independently O or NRii where Rii is an organyl radical, where, in the case that Y1 and/or Y2 is NRi and at least one of the Z1 to Z4 radicals is NRii, Ri together with an Rii radical may also be a bridging group having 2 to 5 atoms between the flanking bonds,and their use as n-semiconductors in organic field-effect transistors.
The unpublished PCT/EP2007/051532 describes the use of compounds of the general formula
where
n is 2, 3 or 4,
at least one of the Rn1, Rn2, Rn3 and Rn4 radicals is fluorine,
if appropriate at least one further Rn1, Rn2, Rn3 and Rn4 radical is a substituent which is selected independently from Cl and Br, and the remaining radicals are each hydrogen,
Y1 and Y2 are each O or NRi where Ri is hydrogen or an organyl radical,
Z1, Z2, Z3 and Z4 are each O,
where, in the case that Y1 and/or Y2 is NRi, one of the Z1 to Z4 radicals may also be NRii, where the Ri and Rii radicals together are a bridging group having from 2 to 5 atoms between the flanking bonds,
as semiconductors, especially n-semiconductors, in organic electronics, especially for organic field-effect transistors, solar cells and organic light-emitting diodes.
The unpublished PCT/EP2007/053330 describes the use of compounds of the general formulae I and II
wheren is 1, 2, 3 or 4,the Rn1, Rn2, Rn3 and Rn4 radicals, when n=1 or 2, are each independently selected from hydrogen, F, Cl, Br and CN, and, when n=3 or 4, are each independently selected from hydrogen, F, Cl and Br,the Ra and Rb radicals are each independently selected from hydrogen and alkyl,the Rc and Rd radicals are each independently selected from groups of the formulae II.1 to II.5:
in which    # is the site of attachment to the imide nitrogen atom,    p is 0 or 1,    x is 2 or 3,    A, where present, is a C1-C10-alkylene group which may be interrupted by one or more nonadjacent groups selected from —O— and —S—,the Ri radicals are each independently selected from C4-C30-alkyl which may be interrupted by one or more nonadjacent oxygen atom(s), where at least one of the Ri radicals in the compounds of the formula II.1 may also be C4-C30-alkyloxy or C4-C30-alkylthio,as n-semiconductors for organic field-effect transistors or solar cells.
K. Müllen et al. describe, in an article in Chem. Mater. 2006, 18, 3715-3725, the use of rylenetetracarboximides and coronenetetracarboximides with branched alkyl radicals on the imide nitrogens as n-semiconductors for organic field-effect transistors and in photovoltaic cells.
K. Müllen and Y. Avlasevich describe, in an article in Chem. Commun., 2006, 4440-4442 which had not been published at the priority date of the present application, dibenzopentarylenetetracarboximides as ring-extended rylene chromophores and their use as NIR-absorbing dyes.
It was an object of the present invention to provide organic compounds which absorb at a particularly long wavelength and can therefore also be used advantageously in combination with lasers which emit at high wavelengths (from 940 to 980 or in particular 1064 nm). It is a further object of the present invention to provide such compounds for use in organic electronics and photovoltaics, especially as semiconductors in excitonic solar cells.